1. Field of the Invention
This invention relates to the production of liquid oxygen and/or liquid nitrogen.
As energy has become more expensive, enormous effort has been expended in trying to reduce the specific power consumption of installations designed to produce liquid oxygen and/or liquid nitrogen.
2. Description of the Prior Art
Generally, installations for producing in excess of 100 tons a day of liquid oxygen or liquid nitrogen comprise an air separation unit for producing gaseous nitrogen and gaseous oxygen and a liquifier for liquifying one or both gaseous products. The specific power consumption of such plant is typically 900 kW-hr/MT (kilowatt hours per metric ton) of liquid produced.
UK Patent specification No. 1,325,881 describes an installation for obtaining liquid oxygen and/or liquid nitrogen by modifying the air separation unit and omitting the liquifier.
Unfortunately, the specific power consumption of the installations described in UK Patent specification No. 1,325,881 are high and the inventor's object was to devise a modified air separation unit which could produce liquid oxygen and/or liquid nitrogen without a liquifier and would, at least in its preferred forms, have a specific power consumption of not greater than 850 kW-hr/MT of liquid produced.